Refrigerant compressor lubrication arrangement



April 26,` 196s s. A. PARKER 3,248,044

REFRIGERANT COMPRESSOR LUBRICATION ARRANGEMENT Wm 47m/mers April 26, 1966 s. A, PARKER 3,248,044

REFRIGERANT COMPRESSOR LUBRICATION ARRANGEMENT Filed Sept. 28, 1'964 3 Sheets-Sheet 2 April 26, 1966 s. A. PARKER 3,248,044

REFRIGERANT COMPRESSOR LUBRICATION ARRANGEMENT Filed Sept. 28, 1964 3 Sheets-Sheet 3 By, um 9L @77M Arm/wrs United States Patent O This invention relates to a refrigerant compressor and, more particularly, to an improved hermetic refrigerant compressor of the type including a vertically extending crankshaft journaled in upper and lower bearings in a compressor block and having improved meansl for lubricating the upper bearings and returning lubricant from the i upper bearings to the sump in a path separate from the ow path of suction gas through the compressor Ito vprevent entrainment of lubricant in the suction gas.

The trend in the refrigeration industry is :toward more compact refrigerant compressors driven at relatively high speeds. In one type compressor design, a vertically extending crankshaft or drivelshaft is-journaled in upper and lower bearings in a compressor block that is resiliently supported within :the sealed outer casing. The drive motor for the crankshaft is loca-ted above the compression mechanism in the compressor block.

Lubrication of the upper bearings has long been'a problem. Lubricant must be supplied to `the upper bearing surfaces on the crankshaft from the reservoir or sump defined in the bottom of -the outer casing. One method of lubricating the upper bearingsurfaces is to provide pump means in the crankshaft for raising lubricant from the sump to the required bearing surfaces. Often eX- cess oil will be pumped from the top of the upper bearing into the motor compartment and be entrained in the suction gas commonly used to cool the motor for driving the crankshaft. The oil which is picked up in the suction gas reduces the oil in the sump and threatens proper bearing lubrication. Further, oil pumped into the refrigeration system will coa-t the interior of the heat exchangers, that is, the condenser and the evaporator, and act as an insulator, thereby reducing heat :transfer between the -refrigerant in the heat exchanger and the medium which is passed in heat exchange relationship with the heat exchanger. In addition, the eliiciency of the compressor may be impaired if oil is entrained in the suction gas. l

Another problem encountered with hermetic refrigeration compressors is that the refrigerant commonly employed, as for example, a hydrofluorocarbon having the trade name Freon, tends, to be miscible in the lubricant. The use of a relatively large supply of oil with a rela-tively small quantity of refrigerant would reduce or obviate the adverse effects caused by miscibility of the refrigerant and oil. However, use of a large supply of oil requires a large sump or reservoir and thus undesirably increases the size of the compressor. 'Ifhe trend is toward miniaturization of compressors coupled with minimization of the quantity of oil within the compressor.

It is desired in compressor design :that the pumping rate of oil be as low as possible and in present design,

an Videal pumping rateV is considered to be one percentl or less by weight of oil for the entire refrigerant and oil mixture. If .the pumping rate is too high, the oil level in the compressor will be endangered and in Vthe event of a high side leak, that is a leak between the compressor and the expansion means, oil will be lost from the reservoir or sump in a short time and compressor failure may result.

An object of the present invention is -to provide a hermetic refrigerant compressor having means inthe drive 3,248,944 Patented Apr. 26, 1966 shaft for lubricating the upper crankshaft bearing while preventing oil from being pumped from the compressor.

Another object of the present invention is -to provide a reciprocating compressor with means in the crankshaft for pumping lubricant from the sump to the upper bearing means, means for sealing the upper bearing means from the motor, and means in the crankshaft forl assuring return of lubricant from the region of the upper bearing means -to the sump in a path separate from the flow compressor by entrainment in the suction gas. Further Y objects and advantages of this-inventionl will be readily perceived from the following description.

The attached drawings illustrate preferred embodiments of my invention, in which:

FIGURE l is a view partly in section and partly in elevation of a compressor embodying the present invention;

FIGURE 2 is an enlarged cross-sectional View illustrating Vthe portion of the drive shaft journaled in lthe upper bearing means;

FIGURE 3 is a view partly in section and partly in elevation of modiiied means for lubricating the upper bearings journaling the drive shaft while preventing lthe lubricant from being entrained in the suction gas;

FIGURE 4 is an enlarged detail View of the upper bearing of the compressor shown in FIGURE 3, more clearly illustrating the slinger construction; and

FIGURES 5 and 6 are detail views of a modied construction utilizing an ejector pump in theiiywheel portion of the crankshaft for assuring proper pumping action in certain designs.

Referring to FIGURE 1, thereV is illustrated a refrigerant compressor 10 embodying the. presen-t invention. The compressor comprises a gas-tight housing including an upper shell 12 and a lower shell 13 integrally joined to one another, as for example, by welding. A plurality of legs 14 may be aiiixed to the lower shell 13 ofthe compressor for supporting the compressor in an upright position.

Resiliently supported within the outer housingor casing of the compressor 10 is a compressor block 15 which comprises a motor ange portion 16 and a cylinder crankcase portion 17 divided by a partition 18.

Surrounding the lower portion 17 lof the compressor block or crankcase in spaced relationship to the lower shell 13 of the outer casing is an annular sleeve 20. Formedintegrally at the top of the annular sleeve 20 is an out-turned, ring-like iiange 21. An annular member 22 having a transversely disposed lower ring-like flange 23 is aixed to the lower shell 13. A plurality of resilient spring means 24 are provided between the ange members 21 and 22 for resiliently provided between the flange members 21 and 22 for resiliently supporting the compressor block 15 within the outer housing'of compressor 10.

Formed Within the compressor block 15 are a plurality of cylinders 26. Although a four-cylinder compressor is illustrated, the compressor may have more or less cyl- Vinders as will be understood by those versed in the art. Cylinder sleeves or liners 27 are provided in each of the cylinders 26 and a suitable piston 28 is adapted to recipi tion valve or reed 39.

sembly 36. Such valve assembly may comprise a discharge valve unit 37, a suction valve plate 38, and a suc- Each valve assembly 36 is retained in position in the end of the cylinder by Ymeans including a cap 40 ixed in position by a Belleville spring or head washer 42 and a retaining ring 44. The cap or cylinder head 40 is sealed with respect to the wall of the cylinder 26 by means of the O-ring 45.

Provided on the compressor block 15 are a pair of'annular circular sealing anges 4S and S0. 'These anges are provided with recesses within which arerdisposed O-rings 52 and 54 for sealing between the annular sleeve 20 and the respective Bauges 4S and 50.A Defined be- `tween the exterior of the compressor block or crankcase 'and the annular shell 2G is a space 56 into which discharge gases are passed from thecylinders 26 after compression.V The hot discharge gases pass from the annular chamber 56 through a conduit S7 to the condenser of the refrigerating system in a known manner. The annular space `56ris preferably provided with a plurality of cavities to impart a mufiiingretfect to the discharge gases which pass through space 56 from the cylinders of the compressor to the conduit 57. Y

Suction gas enters the casing of the compressor via suction line 62 which is aixed to the casing of the compressor. Annular heat shield115 minimizes heat transfer between' the suction gas and the discharge gas, preventing undesirable increase in suction gas temperature. The suction gas'passes through a maze or space 64 defined between the flanges 21 and 23 into the top portion of the compressor. The'suction gas then passes through open-k ing 67 in the end cap or motor vcap 65 aixed to the motorY flange portion 16 of the compressor block and down over the electric drive motor 69, thereby cooling the motor. The suction gas passes through the motor compartment into the valve assemblies 36 and associated cylinders 26 via passage means comprising openings 70 in the partition 18 and openings 71 in the valve assembly 36. Thus, it is seen -that the interior of the hermetic casing between the .compressor block and the outer casing is substantially at suction pressure.

The motor 69 comprises a stator 72 which is mounted within the motor flange portion 16 of the compressor block 15. The stator 72 isiinductivelyrconnected to the rotor 74 which is affixed to the upper portion 76 Vof the drive shaft 30, as for example, by a key 75.

The drive shaft 30 isjournaled in upper bearing means Y erant gas. For properpumping action, the Vflow of oil.;

I pv=density of vapor in passage 99 Y 78 and lower bearing means 84) in the compressor block Y 1S. As shown in FIGURE 1, the lowerbearing means comprise an annular ring-like-member made from suitable bearing material and supported in bearing head S3 which is secured to compressor block 15 by retaining ring 79. The upper bearing means comprise a iirst` bearing 81 and a second bearing 82 spaced from the rst bearing and cooperating therewith to dene an annular space 84 about the shaft 30 and between'the two bearings.

Provided in the shaft 30 are pump means for lubricating the upper andY lower bearing means. Such pump meansI may comprise a vertically extending passage 86 inthe shaft 30, which passage is offset from the axis of rotation of shaft 30 and is communicated with the eye 88 of the Y pump means in the shaft by means of a lateral or transversely disposed passage S9. The eye 88 of the pump means communicates with the sump 90 Vdefined between the lower shell 13 and the annular sleeve 20 via a passage 91 in the thrust Washer 92 and an opening in the lower bearing head 83. Filter orrscreen member 93 is affixed to lower bearing head 83;

The upper end of the passage 86 communicates with Y the bearing surfaces between the shaft 30 and bearings 81 and 82 via lateral passages 94 and 95.

Normally, lubrication oil for the uppermost bearing S1 tends to be drawn over theV upper bearing as a result of Ythe pressure differential existing at the top of the compressor block adjacent to bearing S1. Such oil can be- 4. 1 t come entrained in theV Vsuction gases passing over the motor 69 and may pass Vthrough the opening 70 and into the cylinder 26 through the suction valve 39. Such loss of oil from the sump might impair bearing lubrication.

Further, oil may carry over into the refrigeration system rnust be from passage 97 through passages 98 and 99. It

has been determined thatproper pumping is dependent:

upon the respective radii or lengths of passages 97l and 99 and the respective densities of material in the passages.

AtY apredetermined adverse condition for normal'air conditioning and heat pump applications, the ratios of th radii to the densities are as follows: p l

@La Y 1l12v-Pv where r1=ef`fective length of passage 97 r2=etfective length of passage 99 p1=density of liquid in passage 97 In one typical present application, assume a harsh design condition wherein passage 97 is filled with oil or oil and refrigerant liquid and passage 99 is illed with refrigerant Vvapor and further assume the refrigerant is at 0 F. andk the vapor is superheated at 10 F. Under these circumstances, ,91:62.4#1/ cu. ft.Yand pv=.7l6#/cu. ft. Therefore, Y.

E:site

pv n

for this particular design.V The foregoing further assumes that the gas is essentially incompressible and there are no gas. Thus, it is seen that must be greater than 87.3 for proper pumping action. From the foregoing, the respective lengths of passages 97 and 99 may be theroretically determined.

It will be appreciated that the vertical passage may beV disposed in shaft 30 odset from the axis of rotation. This is provided. Y I have found that the pumping force may be materially increased without increasing pump size by l utilizing an ejector pump in the lower transverse passage.

In FIGURES 5 and 6, there areillustrated details of a Ymodified compressor having an ejector pump arrangef` ment. An elongated generally cylindrical nozzle'120 `is provided in the passage 99'; At one end, the nozzle communicates with passage 98. The other end of the nozzle lis disposed in passage 99' so as toY provide an annular space therebetween. Passage 99' communicates with the i eye 88 of the pump via passage 121. In operation, oil will be pumped from the sump via passage 121 as shaft 30 rotates and discharged through passage 99. The high velocity of the oil passing the free flared end of.. nozzle will create a suction efrect and fluid will be drawn through passages 97 and 98 and the nozzle 120 and discharged from the end of passage 99 into the crankcase. Such construction materially increases the pumping action for a given size machine.

available energy losses from work or friction from the ,which communicates with a generally longitudinally disposed passage 98. The passage 98, which is drilled in shaft 30 and then plugged at the end, is connected at its lower end with a transverse or lateral passage 99 formed in the counterweight portion 100 of crankshaft 30. The passage 99 functions as a pump to draw oil through the return passage means. Thus, it is seen that oil that might tend to become entrained in the. suction gas is positively returned to the crankcase by means of the return passage within the drive shaft 30. The oil may be returned to jthe sump via passages 102 formed in the lower bearing head 83 and communicating the interior of the crankcase with the sump.

Referring now to FIGURES 3 and 4, there is illustrated a compressor embodying a Vmodified arrangement for lubricating the upper bearing means While preventing the entrainment of oil in the suction gas. In this embodiment of the invention, means are provided for positively sealing the upper bearings from the motor compartment and also means are provided for slinging lubricant from the surface of the drive shaft and returning same to the sump.

The sealing means comprise an annular washer-like member 108, made from a suitable sealing material, as for example Teon, and disposed about the drive shaft in spaced relationship to the upper bearing 81.

Between the bearing 81 arrd the chamber 110 defined between the seal 108 and the bearing 81 are passage means for communicating the chamber 110 with the annular space 84 between the bearings 81 and 82. The

passage means 112 may comprise a groove formed in the. exterior surface of the bearing 81 or a groove formed in.

the mating surface of the compressor block adjacent to the upper bearing 81. y

Gperatively atiixed to the shaft 3Q and movable within the chamber 110 is a slinger ring 114. The slinger ning preferably comprises -a resilient O-ring. If desired, an annular metallic, ring-like member may be affixed to the shaft. 'Ihe slinger ring 1'14 functions to brake the sur face tension of the oil particles and direct the oil particles away from the surface of shaft 30. The slinger ring 114 slings oil from the shaft and aids in returning oil or lubricant from the upper bearing means to the sump via the return passage means in the shaft' 31). The return passage means comprise a laterally or transversely disposed passage 1.16 in shaft 30 which communicates the generally the lubricant contained in the sump, While at the same time providing for a relatively low pumping rate of oil. As aforenoted, it is desired in compressor design that the pumping rate of oil should be as low as possible commensurate with the desired result of assuring proper lubrication of the bearing surfaces. Ihe present design reduces the oil in circulation and thereby minimizes the likelihood that the eliioiency of the compressor and of the refrigerating system will be adversely effected by having too much oil in circulation.

Further, the present compressor design uses only a 'relatively small quantity of oil in the compressor. The space necessary to house the oil may be minimal, thus permitting a more compact compressor design. Thus, it is seen that by the present invention, improved compressor lubrication means have been provided in an efficient and relatively inexpensive m-anner.

While I have described presently preferred embodil crankcase, piston means movable in said cylinder means,

a vertically disposed drive shaft in said crankcase, upper bearing means for journaling the crankshaft, the upper end of said crankshaft being operatively connected to a motor, the lower end of said crankshaft extending into a lubricant sump in said housing, conduit means for conveying discharge gases from said cylinder means, conduit means for discharging suction gas into said housing for passage over said motor toV said cylinder means, the improvement comprising first pump means in said crankshaft for forcing lubricant from the sump to said upper bearing means for' lubricating the upper bearing means, and second pump means in said crankshaft for returning lubricant from the region of said upper bearing means in a path separate from the ow path of suction gas to prevent lubri v cant from being entrained in the suction gases passing 4 over the motor into the cylinder means.

longitudinally extending passage 98 in the shaft with the annular space 84. The lower end of the vertically extending passage communicates with a transversely or laterally disposed passage 99 in the counterweight portion 100 of the shaft 30 for returning oil to the lower portion of the compressor block. Oil in the crankcase may return tothe sump 90 deiined between the exterior of the annular shell 20 and the interior of the outer casing through opening 102 defined in lower bearing head 83. The modified construction of I'IGURl-Fl 3 has means for separately'sealing the upper bearing from the motor compartment and also means for positively breaking the surface tension of lubricant on the drive shaft and returning the lubricant to the sump from the upper bearing region.

The reason that seal means are desirable between the upper bearing means and the motor compartment is because of the resultant pressure differential at the top of the upper bearing means tending to draw oil out from the bearings into the motor compartment. As aforenoted, the

2. A reciprocating compressor as in claim 1 including means for sealing the upper bearing means from the motor.

3. -In a reciprocating compressor, a housing, means dening a crankcase in said housing, cylinder means in said crankcase, piston means movable in said cylinder means, a vertically disposed drive'shaft in said crankcase, upper bearing means for journaling the crankshaft, the upper end of said crankshaft being operatively connected to a motor, the lower end of said crankshaft extending into a lubricant sumpin said housing, conduit means for conveying discharge gases from said cylinderrneans, conduit means for discharging suction gas into said housing for passage over said motor to said cylinder means, the im bricant is pumped through the crankshaft to the upper.

bearing means and then returned through the crankshaft in a flow path separate from the path of the suction gas;

`4. In -a refrigerant compressor of the type comprising a vertically disposed drive shaft journaied in upper bearing means in a compressor block and having the lower end thereof immersed in 'lubricant contained in a sump in the compressor, first passage means in said drive shaft communicating with said lubricant in said sump, a lateral passage connecting said lirst passage means-With a vertical duct in said drive shaft olfsetkfrom the longitudinal axis of said drive shaft, lateral passage means communicating the exterior of said drives-haft with said vertical-duet for lubricating the upper bearing means, the improvement comprising a relatively short lateral return passage in the drive shaft communicating 4with -t-he exterior of the drive shaft adjacent to the upper bearing means, a vertically disposed return duct communicating with the `lateral return passage and a relatively long lateralreturn passagel in the drive shaft communicating with the vertically dis- Y posed return duct for returning llubricantto the sump in the compressor. i

5. A refrigerant compressor as in claim 4 including means on 4the drive shaft for breaking the surface tension of the lubricant and returning lubricant through the relatively short lateral return passage, thereturn duct, and the relatively long lateral return passage in the drive shaft.

6. In a reciprocating compressor, a housing, means dening a crankcase in said housing, cylinder means inY said crankcase, piston means movable in said cylinder means, a vertically disposed drive shaft in said crankcase, upper bearing means for journaling the drive shaft, the upper end of said drive shaft being operatively connected to a motor, the lower end of said drive'shaft rextending into a lubricant sump in said housing, means for conveying discharge gases from'said cylinderimeans and out of said'housing, means for receiving suction gas into said housing from a suction line for passage over said motor to said cylinder means, the improvement comprising pumpmeans in said drive shaft for forcing lubricant from the sump to said upper bearing means for lubricating the upper bearing means, means disposed about the drive shaft for sealing the upper bearing means from thepmotor, said upper bearing means comprising a rst upper bearing and a second lowerbearing spaced from said rst bearing so as to deline an annular space about the drive shaft between said bearings, groove means between-the first upper bearing and the crankcase for communicating the top of said upper bearing with said annular space, return passage means 1 dened in thedrive shaft for returning lubricant from said annular space to the sump, and slinger means adjacent the top of said first upper bearing for linging lubricant from the shaft and through said groove means, annular space and return Vpassage means, whereby lubricant `passes through the drive shaft to the upper bearing means and is thenl returned through the drive shaft in a ow path separate from the path of the suction gas.

7. In a reciprocating compressor, la housing, means defining a crankcase in said housing, cylinder means in said crankcase, piston means m'ovabfle in said cylinder means, a Y

vertically disposed drive shaft in said crankcase `having an enlarged flywheel portion, upper bearing means for journaling the crankshaft, the upper end of said crank- .shaft being operatively connected to a motor, the lower crankshaft for forcing lubricantfrom the sump to said up- Y per` bearing means for lubricating the upper bearing means, means for sealing the upper bearing means from the motor and means in said crankshaft for returning lubricant from the lregionA ofV said upper bearing means to` the sump in a pa-th separate from the ow path of suction gas through the compressor to prevent entrainment of lubricant in the suction gas, said lubricant returning means including a rst transverse passage, a vertical-ly disposed passage communicating at one,V end with said rst trans-` verse passage, a second transverse passage in said flywheel portion of said drive shaft; and an ejector nozzle in said seconditransverse passage communicating at one end with .said vertically disposed passage for increasingY the flow of lubricant through said lubricantreturning means.

Y References Cited by the Examiner t UNITED STATES PATENTS 2,963,113 12/1960 Ayling 230-206 X ROBERTM. WALKER, Primm Examiner.

3/1937Y Berry 230-207 Xl v 

1. IN A RECIPROCATING COMPRESSOR, A HOUSING, MEANS DEFINING A CRANKCASE IN SAID HOUSING, CYLINDER MEANS IN SAID CRANKCASE, PISTON MEANS MOVABLE IN SAID CYLINDER MEANS, A VERTICALLY DISPOSED DRIVE SHAFT IN SAID CRANKCASE, UPPER BEARING MEANS FOR JOURNALING THE CRANKSHAFT, THE UPPER END OF SAID CRANKSHAFT BEING OPERATIVELY CONNECTED TO A MOTOR, THE LOWER END OF SAID CRANKSHAFT EXTENDING INTO A LUBRICANT SUMP IN SAID HOUSING, CONDUIT MEANS FOR CONVEYING DISCHARGE GASES FROM SAID CYLINDER MEANS, CONDUIT MEANS FOR DISCHARGING SUCTION GAS INTO SAID HOUSING FOR PASSAGE OVER SAID MOTOR TO SAID CYLINDER MEANS, THE IMPROVEMENT COMPRISING FIRST PUMP MEANS IN SAID CRANKSHAFT FOR FORCING LUBRICANT FROM THE SUMP TO SAID UPPER BEARING MEANS FOR LUBRICATING THE UPPER BEARING MEANS, AND SECOND PUMP MEANS IN SAID CRANKSHAFT FOR RETURNING LUBRICANT FROM THE REGION OF SAID UPPER BEARING MEANS IN A PATH SEPARATE FROM THE FLOW PATH OF SUCTION GAS TO PREVENT LUBRICANT FROM BEING ENTRAINED IN THE SUCTION GASES PASSING OVER THE MOTOR INTO THE CYLINDER MEANS. 